Signaling messages are used within communications networks to communicate information related to call setup, call tear down, call timing, billing, messaging and many related functions. Signaling messages are processed by various applications to achieve the desired functions. Examples of signaling message processing include triggerless processing of ISDN user part (ISUP), telephone user part (TUP), transaction capabilities application part (TCAP), mobile application part (MAP) and session initiation protocol (SIP) signaling messages in a multi-application environment. Some of the message types, such as ISUP and SIP messages relating to call setup, may be subjected to triggerless processing by a signaling message routing node. “Triggerless processing,” as used herein, refers to the processing of a received signaling message without requiring an end office trigger to initiate the processing. For example, a signal transfer point (STP) may perform triggerless processing of received ISUP IAM messages requiring local number portability (LNP) lookups by performing LNP database lookups for the IAM messages without requiring end office trigger to initiate the lookups. Another example of triggerless processing that may be performed for received signaling messages includes screening. For example, received ISUP messages may be screened based on one or more parameters in each message and either routed to their respective destinations, or blocked, depending on the results of the screening.
Signaling messages are routed in communications networks through network elements for processing. Some examples of these network elements include an STP, a signaling system number 7 (SS7) Internet protocol (IP) signaling gateway (SG) (collectively SS7-IP SG), an SS7 gateway, a SIP server, a short message gateway (SMG), a softswitch (SS), and a media gateway controller (MGC).
When a signaling message is routed, the signaling message may be routed through and by any of these network elements. Some network elements may include screening functions or modules (hereinafter referred to as screening functions). Screening functions have traditionally been adapted to apply a screening policy to a received signaling message and to route the signaling message after the screening policy has been applied.
Screening policies may include a variety of processing tasks for any given signaling message. These processing tasks may include processing by one or more message processing applications. Example message processing applications include triggerless pre-paid service applications, number portability service applications, location portability service applications, usage measurements service applications, billing service applications, advanced/intelligent routing service applications (e.g., time of day routing, etc.), messaging service applications (e.g., short message service, multimedia message service, instant message service, etc.), presence service, ENUM service, and other signaling message-based network service applications.
Traditionally, screening policies have been implemented by screening functions that manage all aspects of the processing. These screening functions have acted as a cog in a wheel by placing themselves logically in the middle of several processing applications and sequentially sending signaling messages to applications one at a time for processing (as if sending them along the spokes of the wheel to each application). When signaling message processing is completed by any given application, the message is then sent by the application back to the screening function. The screening function then determines, based upon the screening policy, which application should process the message next and sends the message to that application. This repeats until all message processing is completed and the message is received back at the screening function. With the screening policy complete, the screening function may then route the signaling message to the next node in the network.
By handling all processing and routing decisions for every message, screening functions have traditionally managed all aspects of signaling message processing and routing. The traditional approach burdens the screening function with repeated message processing and routing tasks. This repeated processing burden consumes valuable signaling link bandwidth and requires a substantial amount of time.
For example, the SS7 signaling protocol includes various call setup timers that effectively limit the delays that can be incurred between network elements during call setup operations. Each time a signaling message is routed to the screening function and the screening function has to receive and process the message, an element of time delay is introduced. This repeated processing by a screening function may cause the maximum latency permitted by the SS7 ISUP call setup timers to be exceeded.
Bandwidth is also consumed on the order of 2N (where N is the number of applications). To clarify, for each application required to implement a given screening policy, two transmissions of the message occur: one from the screening function to the application; and another from the application back to
Accordingly, in light of these difficulties associated with conventional message screening, there exists a need for improved methods, systems, and computer program products for screening policy implementation.